The present invention relates to closures for containers, and more particularly to flexible closures adapted to be secured on the containers.
Packing containers for liquid contents, e.g. beverage packages of the bottle type, are usually closed with the help of closing arrangements of substantially two types, namely caps which are not deformed when the packing container is opened, and which therefore may be used for reclosing of the same, and caps which are deformed on opening.
Among the firstnamed type are first and foremost the conventional screw cap, which owing to its reclosability continues to be used to a considerable extent, especially on larger packing containers. However, the cap is relatively expensive to make and to apply to the packing container and it is, moreover, often difficult to open, especially for persons with diminished manual strength.
Among the other type of closing arrangements, that is to say closing arrangements which are deformed on opening, is e.g. the crown cap. This cap comprises an axial jacket whose diameter is reduced as it is fitted on, so that the jacket embraces an outwardly directed bulge or flange located at the mouth end of the container neck. When the closing arrangement is to be removed, a special tool is used which widens the jacket again so that it can pass the bulge, and the cap can be removed. In this process the cap is deformed, however, to such an extent that any reclosing becomes quite impossible.
Neither of the two abovementioned types of caps thus fulfills at the same time the demand for good openability and the possibility of reclosing. It is the object of the present invention, therefore, to provide a closing arrangement which meets the abovementioned demand and which, moreover, at a competitive cost produces a closure with satisfactory tightness.
In recent times it has become more and more usual to manufacture packing containers for e.g. carbonated refreshing beverages in the form of plastic bottles of large volume, e.g. one or two liters. These plastic bottles are made with very thin walls and therefore will be inexpensive to manufacture, while, owing to the orientation of the plastic material carried out in connection with the manufacture, they have at the same time sufficient strength to withstand the internal pressure in the bottles. However, the bottles are very susceptible to axial stresses of the type which arises when on a capping machine a cap is to be applied over the emptying opening, and this step therefore must take place at relatively low speed which appreciably limits the capacity of the filling machine. This disadvantage can be partly overcome, in that the packing container is provided with a neck portion of greater wall thickness. This portion has a strong external flange which serves as a holder-up during the capping process. This prevents the container body itself being subjected to axial stresses. However, this is achieved at the expense of an appreciably higher material consumption and greater complexity of the filling machine.
It is a further object of the present invention therefore to provide a closing arrangement which can be applied without the packing container being subjected to any appreciable axial stress and which is especially suitable, therefore, to be used jointly with thin-walled packing containers made of plastics.
It is a further object of the present invention to provide a closing arrangement having maneuverable parts which are displaceable between two distinctive positions, namely an open or inactive position and a closed or active position.
It is a further object of the present invention to provide a closing arrangement which in spite of comprising maneuverable parts is manufactured in one piece of flexible plastic material. Previously known closing arrangements with maneuverable locking devices adapted to co-operate with external bulges, flanges, protruding rims or the like on container necks are made of several different parts, which makes manufacture as well as handling more expensive.
Finally it is also an object of the present invention to provide a closing arrangement whose maneuverable part safely remains in active position during the handling of the packing container, and which at the same time is not affected by the high internal pressure which arises with certain contents.
These and other objects have been achieved in accordance with the invention in that a closing arrangement of the type described in the inroduction has been given the characteristic that each one of the locking devices is constituted of a lever which is suspended so that it can pivot at the lower end of the jacket, and which is moulded in one piece with the jacket as well as with the stiffening ring surrounding the jacket, by means of which the levers can be maneuvered jointly to the active position in which they engage with the external bulge or flange of the packing container and press the closing arrangement against the mouth of the packing container.
Preferred embodiments of the closing arrangement in accordance with the invention have been given, moreover, the characteristics which are described below.